GCDCA promotes hepatocellular carcinoma progression through S1PR2/PI3K/AKT-mediated polarization of M2-type macrophages.

BACKGROUND: Disorders in bile acid metabolism are recognized as crucial mechanisms in the occurrence and development of hepatocellular carcinoma (HCC), a leading cause of cancer-related deaths worldwide. HCC progression is intricately linked to immune regulation within the tumor microenvironment (TME), particularly involving tumor-associated macrophages (TAMs) that modulate proliferation, invasion, and immune escape. Although glycochenodeoxycholic acid (GCDCA), a primary bile acid, is suspected to influence HCC, the specific mechanisms by which it affects the TME to drive cancer progression remain unclear. METHODS: This study investigated the role of GCDCA in HCC progression using a combination of approaches. Single-cell sequencing was employed to analyze the TME and identify a highly malignant subpopulation of cancer stem cells (CSCs). In vivo experiments were conducted using a primary liver cancer model to assess the effect of GCDCA intervention on tumor progression and stemness. Mechanistic exploration focused on the role of the S1PR2 receptor, utilizing both macrophage and tumor cell systems to examine the S1PR2/PI3K/AKT signaling pathway and its influence on macrophage polarization. RESULTS: Single-cell sequencing revealed a distinct subpopulation of CSCs with high malignancy within the TME. In vivo, GCDCA intervention significantly promoted liver cancer progression and enhanced the stemness of liver cancer cells. Mechanistically, GCDCA was found to activate the S1PR2 receptor on macrophages, triggering the S1PR2/PI3K/AKT signaling pathway. This activation induced macrophage polarization toward the M2 phenotype, which in turn promoted the growth and stemness of cancer stem cells. CONCLUSION: This study demonstrates that GCDCA drives HCC progression by inducing M2-type macrophage polarization via the S1PR2/PI3K/AKT signaling pathway, which subsequently enhances tumor cell stemness. These findings elucidate a novel mechanism by which bile acids remodel the TME to promote liver cancer, highlighting potential therapeutic targets within this pathway.